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Articles on Trending Technologies
Technical articles with clear explanations and examples
What is the resemblance of COALESCE() function with IF-THEN-ELSE statement?
As we know that COALESCE() function returns first non-NULL value from the list of values. The following IF-THEN-ELSE statement is equivalent to COALESCE() function.IF value1 is not NULL THEN output = value1; ELSIF value2 is not NULL THEN output = value2; ELSIF value3 is not NULL THEN output = value3; . . . ELSIF valueN is not NULL THEN output = valueN; ELSE output = NULL; END IF;
Read MoreWhat MySQL COALESCE() function returns if all the arguments provided to it are NULL?
If all the values in MySQL COALESCE() function are NULL then it returns NULL as the output. It means that this function does not find any non-NULL value in the list.Examplemysql> Select COALESCE(NULL, NULL, NULL, NULL); +----------------------------------+ | COALESCE(NULL, NULL, NULL, NULL) | +----------------------------------+ | NULL | +----------------------------------+ 1 row in set (0.00 sec)
Read MoreHow can we split the name string into two parts by using MySQL SUBSTRING_INDEX() function?
To make it understand, we are using the following data from a table named ‘customerdetail’.mysql> Select * from Customerdetail; +----------------------+----------------------+-----------+---------------------+ | Name | FName | Address | Emailid | +----------------------+----------------------+-----------+---------------------+ | Advik Jhamb | Lovkesh Jhamb | Mumbai | Advik@gmail.com | | Chirag Jai Patil | Raman Jai Patil | Gujrat | chirahp@yahoo.com | | Devansh Singh Rajput | Kishore Singh Rajput ...
Read MoreHow can we split an IP Address into four respective octets by using MySQL SUBSTRING_INDEX() function?
Suppose we have a table named ‘ipaddress’ which contains the IP addresses as its values in column ‘IP’ as follows −mysql> Select * from ipaddress; +-----------------+ | ip | +-----------------+ | 192.128.0.5 | | 255.255.255.255 | | 192.0.255.255 | | 192.0.1.5 | +-----------------+ 4 rows in set (0.10 sec)Now with the help of SUBSTRING_INDEX() function in the following query, we can divide the IP address in four octets −mysql> Select IP, SUBSTRING_INDEX(ip, '.', 1)AS '1st Part', -> SUBSTRING_INDEX(SUBSTRING_INDEX(ip, '.', 2), '.', -1)AS '2nd Part', ...
Read MoreHow many types of selection modes for a JList in Java?
A JList is a component that can extend JComponent class used to display a list of objects that allows the user to select one or more items.There are three types of selection modes for a JList in JavaListSelectionModel.SINGLE_SELECTION: Only one list index can be selected at a time.ListSelectionModel.SINGLE_INTERVAL_SELECTION: Only one contiguous interval can be selected at a time.ListSelectionModel.MULTIPLE_INTERVAL_SELECTION: In this mode, there is no restriction on what can be selected. This is a default mode.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class JListSelectionModeTest extends JFrame implements ActionListener { private JList list; private DefaultListModel listModel; public JListSelectionModeTest() { ...
Read MoreHow can I check the status of MySQL Server?
With the help of ‘mysqladmin’ along with ‘status’ option program we would be able to check the status of MySQL server. It can be used as follows on command line −C:\mysql\bin>mysqladmin -u root status Uptime: 3865 Threads: 1 Questions: 50 Slow queries: 0 Opens: 113 Flush tables: 1 Open tables: 102 Queries per second avg: 0.012
Read MoreHow can we analyze the tables of a particular database from MySQL Server command line?
We need to use ‘mysqlcheck’ client program along with –analyze option to analyze the tables of a particular database. Its syntax would be as follows −Mysqlcheck – u root –analyze db_nameExampleThe following command will analyze the tables of database ‘query’ −C:\mysql\bin>mysqlcheck -u root --analyze query query.cars OK query.copy_cars OK query.countries Table is already up to date query.customers ...
Read MoreHow can we implement a scrollable JPanel in Java?
JPanelA JPanel is a subclass of JComponent (a subclass of a Container class). Therefore, JPanel is also a Container.A JPanel is an empty area that can be used either to layout other components including other panels.In a JPanel, we can add fields, labels, buttons, checkboxes, and images also.The Layout Managers such as FlowLayout, GridLayout, BorderLayout and other layout managers helps us to control the sizes, positions, and alignment of the components using JPanel.The important methods of a JPanel class are getAccessibleContext(), getUI(), updateUI() and paramString().We can also implement a JPanel with vertical and horizontal scrolls by adding the panel object to JScrollPane.Exampleimport java.awt.*; ...
Read MoreHow can we implement editable JComboBox in Java?
JComboBoxA JComboBox can extend JComponent class and it is a combination of a text field and a drop-down list from which the user can choose a value.If the text field portion of the control is editable, the user can enter a value in the field or edit a value retrieved from the drop-down list.By default, the user not allowed to edit the data in the text field portion of the JComboBox. If we want to allow the user to edit the text field, call setEditable(true) method.A JComboBox can generate an ActionListener, ChangeListener or ItemListener when the user actions on a combo box.A ...
Read MoreHow can we find the duplicate values available in a MySQL table by using JOINS?
Suppose we have the following table named ‘stock_item’ in which the column quantity is having duplicate values i.e. for item name ‘Notebooks’ and ‘Pencil’, the column ‘Quantity’ is having duplicate values ‘40’ as shown in the table.mysql> Select * from stock_item; +------------+----------+ | item_name |quantity | +------------+----------+ | Calculator | 89 | | Notebooks | 40 | | Pencil | 40 | | Pens | 32 | | Shirts | 29 | | Shoes | ...
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